Mechanical friction-brake.



Patented Oct. 7, I902.

E. P. COLEMAN &. S. E. HITT.

MECHANICAL FRICTION BRAKE.

(Application filed Nov. 21, 1901.)

2 Sheets8heet I (No Model.)

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No. 7I0,759. Patented Oct. 7, I902. E. P. COLEMAN &. S. E. HITT.

MECHANICAL FRICTION BRAKE.

(Applicltion filed Nov. 21, 190 (No Modal.) -2 Sheets-Sheet 2.

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5 N EIIII 1 UNTTED STATES PATENT OFFICE.-

EDGAR P. COLEMAN AND SAMUEL E. HITT, OF CHICAGO, ILLINOIS.

MECHANiCAL FRICTION-BRAKE.

SPECIFICATION formingpart of Letters Patent No. 710,759, dated October'7, 1902.

Original application filed October 23,1900, Serial No. 34,074. Dividedand this application filed November 21,1901. Serial No. 83.180.tNo'model.)

To all whom, it may concern:

Be it known that we, EDGAR P. COLEMAN and SAMUEL E. HITI, of the city ofChicago, county of Cook, and State of Illinois, have invented certainnew and useful Improvements in Mechanical Friction-Brakes, of which thefollowing is a specification.

Our invention relates to hoisting machinery or similar apparatus inwhich there is a tendency for the load to turn the driving mechanism ormotorbackward, and more particularly to improvements in automaticmechanical brakes for jib, gauntree, or overhead traveling cranesoperated usually by electric power.

Automatic friction-brakes as hitherto constructed are objectionable intheir operation principally by reason of the fact that not more thantwo-thirds of the power of the drivingmotor can be availed of forhoisting purposes after the brake has been set-that is, when theload-pressure is on the brake. They have been further objected tobecause of the vibrations produced by the apparatus during the loweringoperation due to the intermittent gripping and releasing of the brake.

The primary object of our invention is to provide a mechanical brakewhich may be started with a very small expenditure of power over andabove that which is required to actually hoist the load. To accomplishthis, it is necessary to eliminate all possible friction between thedriving-motor and the load-shaft of the brake at the moment of startingthe load, and this has been impossible in the older forms of brakes,chiefly because of an equal distribution of friction between the drivingand load shafts.

A further object of our invention is to provide a mechanical brake whichshall oppose a considerable friction to the backward-turning movement ofthe driving-shaft during the lowering of the load, the advantage gainedresiding in a better control of the electric motor.

Another object of our invention is to provide a brake which during thelowering operation will not produce serious vibrations.

Our invention consists, generally speaking, in a mechanical brakecomprising a stationary friction member, in combination with a revolublefriction member, a load-shaft and a driving-shaft, pressure meansinterposed between said load-shaft and said revoluble driving-shaft iscaused to operate directly upon said, loadshaft and pressure means whenthe driving-shaft is rotated positively an d to operate directly uponthe friction me mber when the load-shaft is rotated in a backwarddirection to lower the load.

Our invention further-consists in the combination, with stationary andrevoluble friction members and load and driving shafts, ofpressure-exertingmeanscomprisinga head carried by the load-shaft andtoggle-links extending between said pressure-head and the revolublefriction member, suitable means being provided upon the driving-shaft,load-shaft, and revoluble member for positively operating said head andsaid member; and, further, our invention consists in variousconstructions and in combination of parts, all as hereinafter described,and particularly pointed out in the claims.

Our invention willbe more readily understood by reference to theaccompanying drawings, forming a part of this specification, and inwhich Figurel is a vertical longitudinal section of a frictions-brakeembodying our invention. (See line 1 P, Fig. 2.) Fig. 2 is a detachedview of the friction-heads and toggle-links. Fig. 3 is a detached viewof a modified form of toggle-link connection. Fig. at is a view of thesame at right angles to that shown in Fig. 3, and Fig. 5 is a section online 5 5 of Fig. 3.

As illustrated in the drawings, 2 represents the casing of ourmechanical brake. This casing is a drum or cylinder having a base bywhich it is attached to any suitable foundation.

3 and i are the ends or heads of the cylinder, and these containbearings 5 and (3 for the shafts 7 and 8 of thevbrake. ings havepacking-glands to retain the oil wherewith the casing is filled.

26 is the oil-hole of the casing and is the only place where oil need beapplied to our brake.

The heads are firmly fastened to the cylinder 2, as they must take thethrust of the friction member, and means whereby said These bear- 1pressure-exerting means, which we arrange within the casing. The casinghead or end 3 forms the stationary friction member of the brake.

11 is the revoluble friction member of the brake. This is journaled onthe driving-shaft 7 and has a long hub or sleeve 12, which latter isprovided with longitudinal grooves 13. The casing is provided with likelongitudinal grooves 17. Between the friction member 11 and the end 3 weinterpose a series of friction-disks 15 and 18, which, alternatelyconsidered, are attached or fastened to the hub 12 and to the casing 2by means of.lugs or keys on the disks engaging in the grooves 13 and 17.The disks 18 have holes through them to fit the hub, and the keys orlugs are integral parts of the disks, which extend into the grooves 13of said hub. The disks 15 have no lugs extending inwardly, but insteadhave lugs 16, that extend into the grooves 17 in the casing or cylinder2. Thus when the member 11 rotates the disks 18 will rotate with it,while the disks 15 will remain stationary with the head 3 of the casing.In this manner a very large frictional capacity is provided for within avery small space, and the friction that is derived from the totalsurface of these disks plus the surfaces of 11 and 3 greatly exceeds thefriction which would be secured by the employment of only two planesurfaces, though of equivalent area.

The driving-shaft7extends entirelythrough the casing and is supported,preferably, by an outside hearing, as shown. The hoistingshaft 8 is asleeve journaled on the drivingshaft. It extends through the bearing 6and carries the hoisting-pinion 9, whereon the load exerts its opposingforce. On the inner end of the hoisting-shaft 8 is the pressurehead 10,for which the casing-head 4 serves as a thrust-bearing. The frictionbetween the pressure-head 10 and the end 4 or thrustbearing is reducedas much as possible. The surface exposed for contact is very smallalways, and we sometimes prefer to interpose a set of balls 10 betweenthe pressure-head and the casing end 4.

25 is a coiled spring arranged around the driving-shaft and tending toforce the pressure-head and the friction member- 11 outward, it beingdesirable to hold the frictiondisks always in contact, though not alwaysunder heavy pressure. The pressure means, device, or coupling iscompleted by the toggle or angular links 20,'which extend between thepressure-head 10 and the friction member 11, their office being toapproach perpendicular positions with relation to the head 10 and thefriction member 11, and thus force said members apart, or, in otherwords, the head 10 being fixed by its thrust-bearing forces the frictionmember 11 tightly against the head 3 through the medium of its severalfriction disks. The links 20 have preferably ball heads or ends, whichare held in ball-sockets provided in the head 10 and the member 11. Thesocket-rings, as shown, are preferably adjustable to take up wear. Asillustrated in Figs. 3 and 4, the ball-andsocket connections maybereplaced by hinged joint connections, with one member of each jointswiveled in the opposite head or member 10 ll. We consider, however,that there is greater opportunity for lost motion in this constructionand prefer the ball-hcads upon the links or struts 20. The normal ornatural positions of the links 20 are shown best in Fig. 2, where itwill be seen that the same occupy an acute position with relation to theheads or disks 1O 11. It will be obvious upon reference to the drawingsthat the stationary friction member (the head 3 and stationary disks 15)opposes a considerable resistance to the revolution of the revolublefriction n1embernamely, the member 11 and associated revoluble disks 18.Therefore, for the moment disregarding the driving-shaft, it will beobvious that the backward-turning effort of the hoisting-shaft 8 willoperate the pressure meansto wit, the head 10 and angular links 20-toforce the revoluble friction member into still firmer frictionalengagement with the stationary friction member, and as there is no forcetending to turn the revoluble friction member except that which is eX-erted through the links or struts 20 the friction member will remainstationary and the pressure-head 10 will be kept from rotation throughthe bracing effect of the struts or links 20. It is in this manner thata load which has been raised is supported and kept from falling at anytime when the drivingshaft is stopped. Thus far means are provided toefiectually support a suspended weight or 1oad; but in addition to thisfunction of the brake it is necessary to enable a further lifting of theload, and it is also necessary to provide for lowering the load. To thisend we provide means in connection with the driving-shaft forcontrolling the operations or relative movements of the pressure-headand the friction member 11. (The toggle-links are idle members except tothe extent that they are struts or braces.) These controlling meanscomprise the pins or keys 23 and 24, which extend through or from thedriving-shaft 7 and project into the recesses or notches 14 and 22,provided in the friction mem ber11 and the head 10, respectively. (SeeFigs. 1 and 5.) These notches are of greater width than the ends of pinsor keys 24, so that the driving-shaft is allowed a slight movementindependent of the members mounted thereon.

The operation is as follows: \Vhen the driving-shaft 7 is turnedpositively to hoist the load, (see arrow, Fig. 1,) the pin 23 engageswith the ends or shoulders 22 of the notch or notches 23 in the sleeve 8of pressure-head 10. The pin 24: does not engage positively with thefriction member 11 at this time, and the result is that thepressure-head 10 is carried forward with relation to the friction member11, and the angle of incidence of the links or struts 20 is increasedand the friction-head 11 is drawn inward to decrease and in practicewholly relieve the driving-shaft from its frictional resistance. It willbe noted that in thus turning the hoisting-shaft 8 and the friction-head10 the driving-shaft encounters only the load exerted on thehoistingshaft 8 plus the very slight frictional resistance of the ballor thrust bearing belonging to the pressure-head 10. The friction member11, which has previously been firmly set or clamped by thebackward-turning effort of the suspended load, is not turned at alluntil after the pressure has been relieved. In this feature our brake isnotably different from others. After the load-shaft has been rotated toraise the load and when the driving-shaft is stopped the slight backwardturning of the load-shaft due to the fall of the load instantly appliespressure to the friction member 11, and the backward rotation of theload-shaft 8 is stopped within a fraction of a revolution.

When it is desired to lower the load, the driving-shaft 7 isreversed-that is,it is turned backwardlyby the reversal of thedrivingshaft electric motor, and instantly the pin 23 will leave itsengagement with the shoulders 22 of the pressure-head, and the pin 24:will engage the shoulders 14 within the friction member 11, and thefriction member 11 will then be positively turned against its ownresistance. Being thus moved forward in advance of the pressure-head 10it will operate to increase the angles of the links or struts 20, thusrelieving the pressure upon the friction member 11 and permitting thehead 10 to follow the turning or revolution of the friction member 11.In this manner a continuous backward rotation of the driving-shaft 7results in a continuous decrement of the friction, and the load willfall steadily and without vibrations in the brake mechanism. During thelowering of the load the driving-shaft works against a resistance which,in effect, is slightly less than the force of the weight or load whichit opposes. This prevents the motor from running away and is aparticularly valuable feature where electric series motors are used,such motors being preferred on account of their easy and simpleregulation and handling. Nhenever the backward rotation of thedriving-shaft is stopped, it is obvious that there will be anindependent backward movement of the load-shaft and the pressure-head toinstantly place the friction member under pressure and stop it, so thatby it the ends of the struts or links will be anchored and prevent thefurther rotation of the head. 10 and load-shaft.

In brief, our mechanical brake has the following advantages: Its partsare entirely inclosed. They may be kept always lubricatet Thedriving-shaft extends entirely through the device, so that there can beno disalinement of the parts. An extremely large frictional resistanceis developed within a very small space, and this resistance is developedwithout great pressure. The torque required for starting a suspendedload is little, if any, in excess of the torque required to actuallyraise the load. The resisting effort of the brake is instantaneous whenthe driving-shaft is stopped. The friction member opposes an almostconstant resistance to the rotation of the driving-shaft, except duringthe actual hoisting operation, at which time it offers no resistance,and, finally, the parts are so constructed and assembled that the takingup of wear is substantially automatic, and all parts being subjected topressure only and free from torque are more reliable, as well as ofgreater durability, than parts of the mechanical brakes hithertoemployed.

It is obvious that various modifications of ourinvention will suggestthemselves to those I skilled in the art, and we therefore do notconfine our invention to the specific construction herein shown anddescribed.

This is a divisional application, the subjectmatter hereof being derivedfrom our pending application, entitled Mechanical brakes for hoistingmachinery, Serial No. 34,074, filed October 23, 1900, and attention isalso directed to our pending application, entitled Mechanical brakes,filed November 21, 1901, Serial No. 83,179.

Having thus described our invention, we claim as new and desire tosecure by Letters 1atent- 1. In a mechanical friction-brake, thecombination with a stationary friction member, of a revoluble frictionmember, a load-shaft, pressure-exerting means interposed between saidload-shaft and said revoluble friction member and attached to both, adriving-shaft and controlling means functionally connecting saiddrivingshaft and said pressure means, substantially as described.

2. In a mechanical brake, the combination with a stationary frictionmember, of a revoluble friction member, a load or hoisting shaft, astationary thrust-bearing therefor, pressure-exerting means extendingbetween said hoisting-shaft and said revoluble friction member andoperatively dependent upon the relative rotary positions of said shaftand member, and means for positively rotating either said load-shaft orsaid friction member, substantially as described.

3. In a mechanical frictionbrake, the combination with a stationaryfriction member, of a single revoluble friction member to cooperatetherewith, a hoisting-shaft, a stationary thrust-bearing therefor,pressure-exerting means interposed between said hoistin g-shaft and saidrovoluble friction member, adapted to exert pressure upon said revolublefriction member upon the relative backward rotation of saidhoisting-shaft, and the driving shaft for positively rotating saidhoisting shaft and said revoluble friction member in either direction tohoist and lower IOC IIO

the load, respectively, substantially as described.

4. In a mechanical friction-brake, the combination with a stationaryfriction member, of a rotary friction member, a hoisting-shaft anddriving-shaft whereon said rotary member and said hoisting-shaft aremounted, a fixed thrust-bearing for said hoisting-shaft, coupling meansinterposed between said driving-shaft and the parts mounted thereon andangularlyoperative pressure means interposed between said hoisting-shaftand said rotating friction member, substantially as described.

5. In a mechanical friction-brake, the combination with a stationaryfriction member and a thrust-bearing, of a hoisting-shaft held by saidthrust-bearing, a rotary friction member arranged between saidstationary member and said thrust-bearing, angularly-operative pressureexerting means operatively connecting said hoisting'shaft and saidrotary member and means for positively driving, in opposite directions,said hoisting-shaft and said rotary member, substantially as described.

6. In a mechanical friction-brake, the combination with a stationarycasing, of the driving-shaft extending therethrough a hoistingshaftmounted on said driving-shaft and extending through the end of saidcasing a rotary friction member arranged within the casing and upon saiddriving-shaft, a pressurehead upon the inner end of said hoistingshaft,a pressure coupling or device arranged between said head and saidmember, and the slot-and-pin connections between said driving-shaft,hoisting -shaft and member, substantially as and for the purposespecified.

7. In a mechanical friction-brake, the combination with the casingadapted to contain a lubricant, provided at one end with a friction-headand at the other with a thrust-bearing, a driving-shaftextending throughsaid casing, a hoisting-shaft held by said thrustbearing and having aslot-and-key connection with said driving-shaft, a friction membermounted on said driving-shaft and having a slot-and-key connectiontherewith, means actuated by the relative rotary movement of saidhoisting-shaft and said member to force said member into strongfrictional engagement with the friction-head of said casing when saidhoisting shaft is turned backwardly and relieve such frictionalengagement when the driving-shaft is rotated in either direction,substantially as described.

8. In a mechanical friction-brake, the combination with the stationarycasing, of the driving-shaft extending therethrough, the friction membermounted on said shaft and in said casing, the friction-disks interposedbetween said member and the end of said casing, said disks beingalternately attached to said member and said casing, a hoistingshaft, athrust-bearing therefor, a pressurehead upon said hoisting-shaft,pressure means interposed between said pressure-head and said member,and driving means provided between said driving shaft, hoisting shaftand member, substantially as described.

9. In a mechanical friction-brake, the combination with a stationaryfriction member, of a revoluble friction member, a drivingshaft and aload-shaft, a pressure-head pro vided in connection with saidload-shaft, having a suitable thrust-bearing, angular pressure-exertingmeans provided between said pressure-head and said revoluble frictionmember, and means whereby the positive and reverse operations of saiddriving-shaft cause the positive rotation of said pressurehead and saidrevoluble friction member, respectively, substantially as described.

10. In a mechanical friction-brake, the combination with a stationaryfriction member of a revoluble friction member, a loadshaft, athrust-bearing therefor, toggle-links provided between said load-shaftand said revoluble friction member for exerting pressure upon the latterwhen the said load-shaft is turned backwardly, and means for positivelydriving said load-shaft and said revoluble friction member in oppositedirections, the one not positively driven,'in each case,following theother, substantially as described.

11. In a mechanical friction brake, the combination with a stationaryfriction member, of a driving-shaft, a load-shaft, a friction membermounted on said driving-shaft and having a slot-and-key connectiontherewith, a pressure head having a suitable thrust-bearing and having aslot-and-key connection with said driving-shaft, and the ball-headedlinks connecting said revoluble member and said driving-shaft,substantially as described.

12. In a mechanical friction-brake, the combination with the casing 2having the ends 3 and 4, of the driving-shaft 7 and the load-shaft 8,the friction member 11 and the pressure-head 10 within said casing, saidhead being fixed to said load-shaft 8, the slotand-key connectionsbetween said drivingshaft and said member and said head, athrust-bearing interposed between said head and said end 4. of thecasing, the frictionmultiplying disks interposed between said member 11and said head 3 and the angular toggle-links arranged between saidmember 11 and head 10, substantially as described.

13. In a mechanical friction-brake, the combination with the casing 2having the ends 3 and 4, of the driving-shaft 7 and the load-shaft 8,the friction member 11 and the pressure-head 10 within said casing, saidhead being fixed to said load-shaft 8, the slotand-key connectionsbetween said drivingshaft and said member and said head, athrust-bearing interposed between said head and said end 4 of thecasing, the frictionmultiplying disks interposed between said member 11and said head 3 and the angular toggle-links arranged between saidmember IOC 11 and head 10 and having universal pivot connectiontherewith, substantially as described.

14. In a mechanical friction brake, the combination of the casing 2having the head or ends 3 and 4, with the driving-shaft 7 extendingthrough said ends, the load-shaft 8 extending through the end 4 andhaving the pressure-head 10 within the casing, a thrustbearing for saidhead, the friction member II mounted on the shaft 7, said member andsaid head having slot-and-key connection with said driving-shaft, thefriction-multiplying disks interposed between said member 11 and saidhead 3, the spring 25 arranged between said head 10 and said menr ber 11and the angular pressure-exerting means arranged between said head 10and said member 11, substantially as described.

15. In a mechanical friction brake, the combination with a stationarycasing, of the driving-shaft extending from one end of said casing andthe load-shaft extending from the other end thereof, a revolublefriction member arranged in the driving-shaft end of said easing, andpressure-exerting means in the load-shaft end of said casing, saidpressure means being automatically operative by the load-shaft andpositively operative by the driving-shaft, substantially as described.

In witness whereof Ihave hereunto set my hand, in the presence of twowitnesses, this

